This paper explores the social and emotional consequences of three major assumptions about human action underpinning breastfeeding promotion campaigns in the UK. Drawing on Joas’s critique of instrumental accounts of rational action, the paper illustrates the ways in which these campaigns firstly contribute to the moralisation of motherhood; secondly value highly individualised, de-contextualised forms of action; and thirdly promote an objectified view of the human body as a pliable instrument of human intentions. The consequences of these assumptions, as they shape the efforts of mothers to care for their babies and young children in complex, unpredictable and often uncontrollable situations, provides the focus of discussion. The paper concludes that a target-driven health-promotion policy, relying on a mechanistic account of social and emotional life, is contributing to the burden of early motherhood in ways that are not conducive to infant and maternal health and attachment.